A hold down clamp of the above-described type is known from U.S. Pat. No. 5,676,367. The above described hold-down clamp has the primary function to hold down a stack being formed by applying a certain pressure before the stack grows big enough to hold by its own weight, whereafter the hold down clamp can be removed, which takes place automatically with a predetermined stack height.
More specifically, when the hold down clamp is used for a stack transfer from the delivery device of a printing machine to a transportation trolley or from the transportation trolley to the paper feeder of the printing machine, it can, as a result of a malfunction, cause a dangerous situation. The hold down clamp can present a danger of injury to operation personnel who can be crushed between the hold down clamp and the stack. Further, the transportation trolley can be subject to an overturning force through the protruding hold down clamp because of the relative movement between the stack and the hold down clamp, e.g., upon lifting the stack under the hold down clamp in excess of the clamp's vertical position.